Sealed thermostatic switch

ABSTRACT

A sealed thermostatic switch comprises thermostatic switch means having a housing enclosing operative components of the switch means and having terminals extending from the housing, a seal body having a well receiving the switch means therein with the terminals extending from the well, a compressible sealing member having apertures fitted over the terminals of the switch means, and a spreader member also having apertures fitted over the terminals. The compressible member and the spreading member have interfitting cam surfaces around the noted apertures and the seal body has a wall portion swaged against the spreader member for pressing the compressible member against the seal body and around the terminals of the switch means to form a sealed structure.

United States Patent [1 1 Beunk et al.

i 1 SEALED THERMOSTATIC SWITCH [75] Inventors: Gerrit ,I. Beunk, Almelo; Arie van der Ploeg, Wierden, both of Netherlands [73] Assignee: Texas Instruments Incorporated,

Dallas, Tex.

22 Filed: July 3,1974

21 Appl.No.:485,402

[52] US. Cl. 337/380; 337/354; 337/369 [51] Int. Cl. HOlh 37/52 [58] Field of Search 337/354, 362, 365,372, 337/380, 381, 369

[56] References Cited UNITED STATES PATENTS 2,667,553 7/1954 Moorhead et al. 337/365 2,752,454 6/l956 Kurtz 337/354 3,356,807 l2/l967 Brown et al. 337/365 X [111 3,893,057 [451 July 1,1975

Primary Examiner-J. D Miller Assistant ExaminerFred E. Bell Attorney, Agent, or Firm.lames P. McAndrews; John A. Haug; Russell R. Baumann [57] ABSTRACT A sealed thermostatic switch comprises thermostatic switch means having a housing enclosing operative components of the switch means and having terminals extending from the housing, a seal body having a well receiving the switch means therein with the terminals extending from the well, a compressible sealing member having apertures fitted over the terminals of the switch means, and a spreader member also having apertures fitted over the terminals. The compressible member and the spreading member have interfitting cam surfaces around the noted apertures and the seal body has a wall portion swaged against the spreader member for pressing the compressible member against the seal body and around the terminals of the switch means to form a sealed structure.

3 Claims, 2 Drawing Figures SEALED THERMOSTATIC SWITCH Electrical switches including thennostatic switches of many difi'erent types are commercially available for use in a wide variety of applications wherein the electrical or thermal characteristics of the switches match the requirements of the application. Where such switches are widely used, the switch devices are usually available at very low cost as a result of the advantages derived from repetitive manufacture. However, where a switch having the desired properties has only limited application, the switch costs are frequently many times higher than the costs of more widely used switches of generally similar properties. In providing a switch to meet the needs of a specific application, it is therefore highly desirable to utilize a switch of a type which is widely used wherever possible. In this regard, however, many electrical switches which are in wide use for various applications are not appropriately sealed against the entry of moisture into the switches. Accordingly, where a sealed switch construction is required, an expensive sealed switch of special construction frequently must be used even though unsealed switches of the desired electrical and thermal properties may be widely available at very low cost.

It is an object of this invention to provide a novel and improved sealed switch construction; to provide such a sealed switch construction which is characterized by low cost; to provide such a sealed switch which incorporates switch components which are available at very low cost; and to provide such a sealed switch construction which is versatile in its applications.

Other objects, advantages and details of the improved switch of this invention appear in the following detailed description of preferred embodiments of the invention, these detailed descriptions referring to the drawings in which:

FIG. 1 is a perspective view of the switch provided by this invention, and

FIG. 2 is a section view along line 2-2 of FIG. 1.

Referring to the drawings, in FIGS. 1 and 2 indicates the novel, sealed electrical switch of this invention which is shown to include an electrical switch means 12 having a housing or frame of generally conventional configuration and having one or more terminals 16 extending from the housing. Typically, the switch means 12 comprises a thermostatic switch means which has a fixed contact 18 and a movable contact arm 20 mounted in the housing 14, and which has a thermally responsive snap-acting disc element 22 at one end of the switch means movable from one dished configuration in an open circuit position to an inverted dished configuration in response to temperature change in the disc for transferring such disc motion through the transfer pin 23 to the movable contact arm 20 for closing the switch. As the switch means 12 is of any conventional type in accordance with this invention, it is not further described herein and it will be understood that the switch means 12 has a frame or housing 14 enclosing operative switch components and has terminals 16 extending in one direction from this housing. Where the switch means 12 is of the thermostatic type, a thermal responsive element of the switch means, such as the disc element 22, is preferably disposed at an end of the housing 14 opposite from the terminals 16 of the switch means as shown in FIG. 2.

In accordance with this invention, the sealed switch 10 further includes a seal body 24 preferably formed of a malleable, heat-conducting metal material such as brass or steel. This seal body has a well 24.1 formed at one end of the body and this end of the seal body is defined by relatively thin wall portions 24.2 of the body. This well is proportioned to receive the switch means 12 within the well with the housing 14 of the switch means in close thermal engagement with the thin walls 24.2 of the body which define the well 24.] and with the terminals 16 of the switch means 12 extending out of the open end of the body well. The seal body is further provided with a shoulder 24.3 completely around the open end of the body well and has a wall 24.4 upstanding from this shoulder. Typically, the wall 24.4 is formed by a counterbore 24.5 in the seal body. If desired, the seal body is provided with exterior screw thread means 24.6 and with a hexagonal outer surface portion 24.7 as shown in FIG. 1. Preferably the upper end 24.8 of the wall 24.4 in the seal body is quite thin as shown in FIG. 2 and for this purpose, where the body is provided with hexagonal outer surfaces, a groove 24.9 is formed in the body around the upper end of the wall 24.4.

A compressible member 26 of rubber or other similar, electrically insulating material such as a nonporous elastomer or the like is provided with apertures 26.] and has these apertures fitted over the terminals 16 of the switch means, the compressible member being proportioned so that the member fits closely within the body walls 24.4 and so that its outer edge 26.2 rests on the shoulder 24.3 of the seal body completely around the body well 24.1. In accordance with this invention, the compressible member has upstanding portions 26.3 around each of its apertures forming cam surfaces 26.4 which surround portions of the apertures and which slope inwardly toward open ends of the apertures 26.1.

A spreader member 28 also formed of electrically insulating material is preferably formed of a substantially rigid material such as a phenolic resin, glass-filled nylon or the like. This spreader member is also provided with apertures 28.1 which are fitted over the terminals 16 of the switch means 12 and is also proportioned to fit closely within the walls 24.4 of the seal body. In addition, the spreader member is provided with recessed portions 28.2 forming cam surfaces 28.3 surrounding the apertures 28.1. These recessed portions of the spreader member interfit with and engage with the upstanding cam-surfaced portions 26.3 of the compressible member.

If desired, as where the switch means 12 has an outer configuration which does not fully conform to the configuration of the seal body well 24.1, spacer means 30 such as an annular ring of a rigid phenolic resin or the like is positioned within the well between the well walls and portions of the housing 14 of the switch means.

In the sealed switch 10, the upper end 24.8 of the upstanding wall on the seal body is formed by swaging or the like for holding the spreader member 28 pressed against the compressible member 26, whereby the compressible member is held in sealed relation to the shoulder 24.3 on the seal body and whereby the cam surfaces 28.3 of the spreader member compress the upstanding portions 26.3 of the compressible member in sealing relation to the terminals 16 of the switch means 12. In this way, the switch means 12 is sealed against the entry of moisture into the switch means in an economical and reliable way. Further, where desired, the

thread means 24.6 on the seal body of the sealed switch are adapted to be engaged with corresponding threads on an automotive radiator or engine block as is diagrammatically illustrated by the broken lines 30 in FIG. 2 for disposing the thin wall portions 24.2 of the seal body within the radiator or engine block to dispose the thermally responsive element 22 of the switch means to be heated by liquid within the radiator or block. The sealed switch 10 is thus adapted to incorporate switch means 12 which are of any conventional configuration including various types of thermostatic and other electrical switches which are widely available from commercial sources at low cost while also being adapted to serve in applications where a sealed switch construction is required.

lt should be understood that although particular embodiments of the switch of this invention have been described by way of illustrating the invention, this invention includes all modifications and equivalents of the disclosed embodiments falling within the scope of the appended claims.

What is claimed is:

l. A sealed electrical switch comprising a seal body having a well therein which is open at one end, having a shoulder extending completely around said open well end, and having a wall upstanding from said shoulder; a switch means having a frame, operative switching components mounted on said frame for performing an electrical switching function, and terminal means extending in a selected direction from said frame for electrically connecting said switch means in an electrical circuit, said switch means being disposed in said well of said seal body with said terminal means extending out of said open well end; a compressible sealing member of electrically insulating material having a portion resting on said shoulder completely around said open well end and having an aperture fitted around each terminal means of said switch means extending out of said well, said compressible member having an upstanding portion with cam surfaces thereon surrounding a portion of each aperture in said compressible member and inclined toward an end of said aperture; and a spreader member of a relatively more rigid electrically insulating material having an aperture fitted around each terminal means of said switch means, said spreader member having a recessed portion around each aperture therein interfitted with an upstanding portion of said compressible member, said seal body having said wall engaging said spreader member pressing said compressible member against said shoulder and camming said upstanding portion of said compressible member around said terminal means of said switch means for sealing said switch means within said body to form said sealed electrical switch.

2. A sealed switch as set forth in claim 1 wherein said seal body is formed of metal and has relatively thin wall portions defining said body well, and said switch means includes a thermostatically responsive element, said switch means being disposed in said well with said thermostatically responsive element in heat transfer relation to said thin wall portions of said seal body.

3. A sealed switch as set forth in claim 2 wherein said seal body has integral screw thread means on an exterior surface thereof for use in mounting said sealed switch. 

1. A sealed electrical switch comprising a seal body having a well therein which is open at one end, having a shoulder extending completely around said open well end, and having a wall upstanding from said shoulder; a switch means having a frame, operative switching components mounted on said frame for performing an electrical switching function, and terminal means extending in a selected direction from said frame for electrically connecting said switch means in an electrical circuit, said switch means being disposed in said well of said seal body with said terminal means extending out of said open well end; a compressible sealing member of electrically insulating material having a portion resting on said shoulder completely around said open well end and having an aperture fitted around each terminal means of said switch means extending out of said well, said compressible member having an upstanding portion with cam surfaces thereon surrounding a portion of each aperture in said compressible member and inclined toward an end of said aperture; and a spreader member of a relatively more rigid electrically insulating material having an aperture fitted around each terminal means of said switch means, said spreader member having a recessed portion around each aperture therein interfitted with an upstanding portion of said compressible member, said seal body having said wall engaging said spreader member pressing said compressible member against said shoulder and camming said upstanding portion of said compressible member around said terminal means of said switch means for sealing said switch means within said body to form said sealed electrical switch.
 2. A sealed switch as set forth in claim 1 wherein said seal body is formed of metal and has relatively thin wall portions defining said body well, and said switch means includes a thermostatically responsive element, said switch means being disposed in said well with said thermostatically responsive element in heat transfer relation to said thin wall portions of said seal body.
 3. A sealed switch as set forth in claim 2 wherein said seal body has integral screw thread means on an exterior surface thereof for use in mounting said sealed switch. 